The present invention generally relates to an ATM cell transferring method and an ATM cell transferring apparatus. More specifically, the present invention is directed to data communication techniques capable of transferring ATM (Asynchronous Transfer Mode) data via a highspeed serial data bus standardized by IEEE 1394.
Recently, communication systems have been proposed in which various electronic appliances such as personal computers, digital video cameras, digital tuners, and hard disk units are electrically connected to each other by employing a highspeed serial data bus standardized by IEEE 1394 (will be referred to as a "1394-serial data bus" hereinafter) so as to communicate digital picture/image signals, digital audio/voice signals, and the like among these electronic appliances. In the above-described data communication systems, since the respective electronic appliances are connected to each other via the cables defined in IEEE 1394 (will be referred to as "1394-cables" hereinafter), the digital image signals and the digital audio signals can be communicated among these electronic appliances. Furthermore, all of these electronic appliances can be controlled in total sense.
On the other hand, ATM (Asynchonous Transfer Mode) is used in networks, e.g., a personal computer LAN (Local Area Network) and a B-ISDN (Broadband Integrated Service Digital Network). It should be noted that this ATM corresponds to such a format defined by ITU-T (International Telecommunication Union-Telecommunication). A packet (normally, called as a "cell") used in an ATM system owns a fixed length of 53 bytes, as illustrated in FIG. 1A, which is constructed of a 5-bite ATM cell header, and a 48-byte payload subsequent to this ATM cell header. Then, the 5-byte cell header owns such a structure as shown in FIG. 1B. Since no synchronous relationship is required between a phase of a frame and a position of a cell, and/or between positions of cells within an ATM network, this ATM system is suitably used to constitute networks where data having various bite rates are communicated in mixture manners. Under such circumstances, strong needs are made of establishing a networks with satisfying both the merits of the abovedescribed communication system and ATM system.